DAKAR, Senegal — Gambia’s ruling party pressed for a fresh presidential election Tuesday as West African regional mediators intervened to try to resolve a mounting political crisis in the tiny country that voted its leader of 22 years from power less than two weeks ago.

A petition signed by the secretary-general of President Yahya Jammeh’s party on Tuesday demanded a new vote with a revalidated voter registry.

The document, which was also signed by a notary public and seen by The Associated Press, says the election was not conducted fairly or in good faith and therefore should be invalidated.

Jammeh initially acknowledged defeat, even calling the Dec. 1 election fair and conceding to President-elect Adama Barrow in a telephone call broadcast on state television. But he announced last week that he was rejecting the election results.

Among the irregularities cited in the petition brought against the Independent Electoral Commission and Gambia’s attorney general were the different results reported the day after the election and again on Dec. 5. It also questioned why some 360,000 registered voters did not make it to the polls.

The commission said the vote was transparent, fair and accurate. The results it gave on Dec. 5 were updated totals, but the commission said the new counts did not change the outcome and that Barrow still was the winner.

Tuesday was the deadline for challenging the election. However, Gambia does not have a sitting Supreme Court, so it was unclear with whom Jammeh’s party, the Alliance for Patriotic Reorientation and Construction, filed its petition.

Gambian security forces blocked access to the electoral commission office, refusing to let staffers enter Tuesday, as several West African leaders arrived to urge the president to respect the elections and allow a peaceful transition of power.

“The president and all the entities have assured us that peace and stability will remain in Gambia as a decision process proceeds to a conclusion,” Liberia President Ellen Johnson Sirleaf, who headed the delegation of West African regional economic bloc leaders, said.

Sirleaf, a Nobel Peace Prize laureate, led separate meetings with Jammeh, President-elect Barrow and the electoral commission head. She was joined by other leaders from the regional economic bloc, known as ECOWAS, including Nigeria President Muhammadu Buhari, Sierra Leone President Ernest Bai Koroma and Ghana President John Mahama, who also was just voted from office.

Sirleaf said the leaders will meet with other colleagues in the regional body on Saturday in Abuja, Nigeria.

The head of the West African regional bloc, Marcel Alain de Souza, had told French radio RFI that military intervention could be considered if Jammeh does not step down. The bloc has warned that the tiny nation of 1.9 million could be plunged into violence, if its leader does not honor the will of voters.

Soldiers remained in the streets Tuesday as Gambians worried about unrest, a stark contrast to days of celebration in the streets after Jammeh’s loss.

Jammeh, who seized power in a bloodless 1994 military coup, has long been accused by human rights groups of overseeing a government that imprisons, tortures and sometimes kills its opponents.

Barrow has denounced Jammeh’s rejection of the vote and said he lacks the constitutional authority to call for a new vote or to declare the Dec. 1 election null and void. Jammeh’s term expires in January.

The United Nations Security Council, the United States and other countries and international organizations have called for a peaceful transition of power.